1. Field of the Invention
This invention generally relates to a printhead controller, and more particularly to a printhead controller of an ink jet printer.
2. Description of Related Art
Computers are widely used in the present era. In addition to displaying the data or images processed by the computer on the display, there are several ways to output the data or images. A printer is one of the most common output devices which can output the text, data, graphics, etc. on the papers.
Currently, the printers can be classified into dot-matrix printers, inkjet printers, and laser printers. Each of these three printers has its own advantages. Hence, users can choose different printers based on their need.
A cartridge installed in a printer can contain ink with one or more different colors. The cartridge jets out the drops of ink, via the nozzles onto the paper to form the text, line, or graphics. Some photo ink jet printers even have the cartridges with pink or pink blue ink for printing images with more colors.
FIG. 1 is an inkjet drive circuit disclosed in the U.S. Pat. No. 6,299,292. As shown in FIG. 1, the drive circuit includes 16 printhead arrays 105. Each printhead array 105 includes 13 heaters H. After the decoder 109 receives the print command, it will send out the address decoding signal of the printhead based on the print command to heat up the heaters H corresponding to the specific addresses so that the ink will be heated and jetted out via the nozzle.
The decoder 109 will send out the printhead array address signals AD1-AD16 and the heater address signals A1-A13. The printhead array address signals AD1-AD16 will determine which printhead array 105 will be driven. The heater address signals A1-A13 will determine which heater H in the specific printhead array 105 will heat the ink. The first terminal of the heater H receives the voltage signal V and the second terminal of the heater H will be controlled by two switches to determine whether current passes through that heater. These two switches comprise MOSFETs 101 and 103. The gate of the MOSFET 103 receives the printhead array address signal; the source (when the MOSFET is a CMOS) receives the heater address signal. When the source and the gate of the MOSFET 103 are enabled at the same time, the drain (when the MOSFET is a CMOS) will generate current signal and send it to the gate of the MOSFET 101. At the time the source-drain of the MOSFET 101 will be turned on when the voltage signal V is supplied, and the heater H will heat the ink and the ink is ready to be jetted out.
FIG. 2 is the inkjet drive circuit disclosed in the U.S. Pat. No. 5,867,183. As shown in FIG. 2, the inkjet drive circuit includes the inkjet printhead drive unit 201 and the printhead ink output units 211 and 213. The inkjet printhead drive unit 201 includes the inkjet printhead drive circuit 203 and the printhead selection circuit 205. The inkjet printhead drive circuit 203 outputs a set of bus control signals 207 and the printhead selection circuit 205 outputs a set of bus selection signal 209 selectively to enable one of the printhead ink output units. The control signals 207 and the corresponding selection signal will determine whether to enable the nozzles of one of the printhead ink output units.
The printhead ink output unit 211 includes the enable circuit 215, the nozzle jetting circuits 225-231 and the nozzle 233. The enable circuit 215 includes a plurality of MOSFETs 217, 219, 221 and 223. The drain (current input) of each MOSFET will receive the corresponding control signal in the bus control signal set 203. The gate (command input) of each MOSFET will receive the corresponding selection signal in the bus selection signal set 209. When the drain and the gate of the same MOSFET are enabled at the same time, the source (output terminal, current output) will generate a current signal to drive the coupled nozzle jetting circuit. For example, the MOSFET 217 is coupled to the nozzle jetting circuit 225 and the MOSFET 219 is coupled to the nozzle jetting circuit 227. Then the nozzle jetting circuit will jet out the ink out of the nozzle 233. The printhead ink output unit 213 works the same as the printhead ink output unit 211.